TeX Quellcode:

\begin{array}{rclcl} x \cdot \ln(x) &=& 2x &\vert& :x \cr \ln(x) &=& 2 &\vert& e^{*} \cr x &=& e^2 \approx 7{,}39 \;\in\;\mathbb{D} \\\\ \mathbb{L} &=& \left\{e^2\right\} \end{array}